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Inside Tract - Putting Barrett's ablation in its place
Inside Tract Winter 2012
Putting Barrett's ablation in its place
Date: November 15, 2011
The Hopkins-invented cryotherapy “is technically very easy to do,” say endoscopists Mimi Canto and Eun Ji Shin, and appears highly effective.
You burn it away or freeze it off.”
That’s gastroenterologist Eun Ji Shin’s shorthand for first-line options for patients diagnosed with the Barrett’s esophagus (BE) that calls for ablation therapy.
Given that BE patients’ risk of adenocarcinoma can be dramatically higher than that of the general population, depending on the degree of dysplasia, says Shin’s colleague Mimi Canto, “we need different techniques to treat or prevent cancer in the variety of patients we see.”
That hasn’t been a snap. Photodynamic therapy, for example, an older endoscopic approach to ablation, could destroy suspect mucosa well enough but had drawbacks. Its light-sensitizing agents worked a little too broadly, setting many patients up for easy sunburn. It had an unacceptably high rate of esophageal stricture.
Fortunately, new approaches have surfaced.
In 2005, Hopkins was quick to adopt radiofrequency (RF) ablation after its NIH-approval. RF is the present workhorse therapy at Hopkins, offered to some 80 percent of appropriate patients.
With the “burn it off” endoscopic procedure, properly positioned bipolar electrodes on a small enclosed paddle ensure a reliable depth of action, hitting only the abnormal cell layer. After a few treatments, dysplasia vanishes 80 to 90 percent of the time, followed by healthy new growth.
But not everyone’s a candidate. “A small portion of patients have RF-resistant mucosa,” Shin explains. “Or there are contraindications,” Canto adds. “Patients who’ve had prior radiation therapy, for example, or those with varices or active inflammation need another option.”
So comes thefreeze. Well before RF ablation was under way, gastroenterologists Tony Kalloo and Pankaj Pasricha conducted animal, then human studies of cryotherapy for bleeding GI lesions. They’d developed an endoscope-based device that delivers freezing CO2 to a site through a plastic catheter.
“Since its invention at Hopkins, we’ve also successfully used cryotherapy to treat early esophageal cancers and the Barrett’s dysplasias that have failed other treatments,” Canto says.
Today, CO2 cryotherapy is the second-line option at Hopkins largely because hard evidence isn’t yet out in journals. From preliminary studies, “cryo” appears to have a high success rate with few side effects. Canto adds, “We see it as a promising alternative.”